After integrated circuit chips are formed, leads must be bonded to them, and then the chips must be encapsulated in epoxy or other protective material. The lead bonding process is commonly performed by providing a thin strip carrier such as a metal lead frame or a plastic metal coated tape such as that sold under the trade mark KAPTON. The required leads are normally preformed on the lead frame or tape and project into openings in the lead frame or tape. The chips are placed in the openings and the leads are then bonded to the chips e.g. by thermal compression bonding (as is well known).
After the leads have been bonded to the chip, the chips are encapsulated, normally by injection molding of a thermosetting plastic or other suitable material around the chips. In the injection molding process a cavity must be closed around each chip and then molten plastic must be directed through runners to the cavities. In the past this process has commonly involved directing the runner over and in contact with the lead frame, causing the plastic when it hardens to stick to the lead frame. This is acceptable for a metal lead frame, since the lead frame is strong and the plastic can be broken away from it during the degating process. However this method is not acceptable for metal coated plastic tape, since the plastic sticks to the tape and cannot be removed without tearing the tape.
As a result, encapsulation of chips mounted in metal coated plastic tape has in the past been a slow batch process, with long cycle times and also commonly involving a considerable amount of wasted plastic.
Similar difficulties have been encountered in encapsulating other electrical components, e.g. resistors, capacitors and diodes. The process would, for example, be faster and less costly if they could be encapsulated in a continuous process. The same applies to other small parts requiring encapsulation.